I was looking to purchase HF amplifier for my FLEX-1500. There is one that looks right on eBay (US $95.00), but I am not able to find any details, documentation or a review that will tell me is it worth purchasing. The unit is made in China and this is 150W HF Power Amplifier TC-300 with FM-AM-SSB-CW Working mode, 3-30Mhz.

Capable of operating on CB frequencies and likely no band switched harmonic filtering.

"§ 97.317 Standards for certification ofexternal RF power amplifiers.(a) To receive a grant of certification,the amplifier must:(1) Satisfy the spurious emissionstandards of § 97.307 (d) or (e) of thispart, as applicable, when the amplifieris operated at the lesser of 1.5 kW PEPor its full output power and when theamplifier is placed in the ‘‘standby’’ or‘‘off’’ positions while connected to thetransmitter.(2) Not be capable of amplifying theinput RF power (driving signal) bymore than 15 dB gain. Gain is definedas the ratio of the input RF power tothe output RF power of the amplifierwhere both power measurements areexpressed in peak envelope power ormean power.(3) Exhibit no amplification (0 dBgain) between 26 MHz and 28 MHz.(b) Certification shall be deniedwhen:(1) The Commission determines theamplifier can be used in services otherthan the Amateur Radio Service, or(2) The amplifier can be easily modifiedto operate on frequencies between26 MHz and 28 MHz."

There are no specs given on harmonic suppression or intermodulation. There's no connection for bandswitching low pass filters, and although there MAY be automatic circuitry inside for that, the whole thing looks a bit too small to have filters in to get harmonics 50dB down as required both by the Radio Regulations and to meet the requirements of EN301 783 - which it must meet to legally have the CE mark.

Don't touch it with a bargepole! That CE mark alone makes me suspicious......it looks to me as if the spacing is wrong, which is a known Chinese manufacturing trick to con people into thinking a device is approved in Europe. Then they say it stands for 'Chinese export'.

Tell Flex Radios to start listening to their customers.Elecraft started with 10 watt K2 and then offered the 100 watt upgrade.The 500 watt amplifier came along a few years ago.

Tom, W8JI comments on RM Italy mobile amplifiers.http://www.w8ji.com/rm_hla-150_test.htmRM HLA-150 testSome people claim an HLA-150 is a very clean amplifier. One odd thing is the transistors are specified for about 70 watts maximum output per transistor, yet RM Italy calls the HLA-150 a "300 watt PEP" amplifier.

A ham can put the biggest piece of home brew crap on the air and it is legal. Yet when someone buys something made off shore without the FCC acceptance label the sky is falling down.

All amplifiers when overdriven will cause problems.

The mic. gain knob causes the most interference on SSB.

The spectral purity of your signal is the responsibility of the operator. No amount of harmonic filtering will cure signal IMD distortion from over driving an amplifier.

Shortly the amplifier police will descend on the post and the Armageddon of the ham bands will commence.

Here is an idea…Why not put one into operation and measure the two tone IMD and harmonic content. Look at the 1 dB compression point. Then if the amplifier needs a harmonic filter build one for the specific band of operation. Post the results and describe the project in the article section. Find out at what voltage the amplifier is most linear. Play with the bias to improve the amplifier IMD performance.

A ham can put the biggest piece of home brew crap on the air and it is legal. Yet when someone buys something made off shore without the FCC acceptance label the sky is falling down.

All amplifiers when overdriven will cause problems.

The mic. gain knob causes the most interference on SSB.

The spectral purity of your signal is the responsibility of the operator. No amount of harmonic filtering will cure signal IMD distortion from over driving an amplifier.

Shortly the amplifier police will descend on the post and the Armageddon of the ham bands will commence.

Here is an idea…Why not put one into operation and measure the two tone IMD and harmonic content. Look at the 1 dB compression point. Then if the amplifier needs a harmonic filter build one for the specific band of operation. Post the results and describe the project in the article section. Find out at what voltage the amplifier is most linear. Play with the bias to improve the amplifier IMD performance.

Another words go back to what ham radio as all about 40 years ago.

I hear you, they rail about an amp that will do 150 watts then post about any ideas to homebrew an amp with a pair of 4CX1500

note also 150 watts PEP on FM but 300 on SSB. also 250 watts out for 5 in, but 10 in for 300 out. Input current 14 -20 amps but 2 blown 12 Amp fuses. Does that mean the fuses have blown open or that they blower cooled? why 2 12Amp and not 20 Amp? Or maybe one fuse for each side of a push pull stage?

One reason for not buying one, measuring it and building harmonic filters is that unless you have the real S parameters for the devices - they may well have a known number but unless the transistors are from a reputable source, the parameters may not be the published ones - you can spend a lot of time getting a filter configuration that enables the amp to stay stable. Plus you need test gear that most hams don't have.

It is not legal for a manufacturer or commercial store to sell an FCC non compliant linear amplifier. It is not illeagle for a anyone to buy a non compliant amplifier. It is not legal for an unlicensed person to use the amplifier. It is legal for a licensed ham operator to use any linear amplifier as long as he monitors it and sets it up for proper FCC compliance.

Now to this CB amplifier garbage. Just about any amplifier be it a 10 meter ham chippie to a megabuck ham unit can be set to illegally operate on 11 meters by a competent technician. The CB operator that uses the amp is the one who breaks the FCC law. Back in the day the 11 meter band was a ham band. My Heathkit DX-35 transmitter with the Heath VF-1 VFO had that band available. Many linear amplifiers back then were capable of operating on the 11 meter ham band with up to 1 KW input power (the power back then was specified as the maximum input power allowed).

Ham radio and the frequency's we use are for experimental radio operation besides rag chews and contests. Many design advances to radio electronics were first developed and used by hams. This is the reason ham radio operators are granted so much bandwith in a crowded radio spectrum.

Buy and use whatever linear amplifier you want, just make sure you operate it in compliance with FCC rules and proper ham radio procedure.

There is no such thing as an illeagle CB amplifier. There are CB radio operators that use linear amplifiers illegally and in non compliance with FCC rules. This is not the amplifier manufacturers or retailers problem. Only the end users problem. The FCC tries to keep non compliance amplifiers out of the hands of non compliant users, but as every on knows this does not work to well. The FCC needs to enforce non compliance radio use and not penalize the hams who use the amplifiers for experimental usage which is what ham radio is all about.

It is not legal for a manufacturer or commercial store to sell an FCC non compliant linear amplifier.

what do you make of this ?

"The FCC called on ePowerAmps to confirm “in writing” that it has stopped marketing unauthorized RF devices and to provide certain information to the commission within 30 days of the C&O. The information request, contained in a non-public appendix to the C&O, seeks to determine ePowerAmps’ “external RF power amplifier suppliers and sales, as well as the disposition of its illegal inventory,” the Commission said. The FCC gave the retailer 30 days to respond to the C&O and even to challenge the FCC’s findings."

You notice that all these Flex 1500 guys are always looking at these illegal CB linears. Another bad side effect of Flex Radio's products.

Well not a bad side of Flex radio. It was designed and sold as a QRP rig and a whole lot cheaper than its brothers that have a 100 W PA. People buy on the cheap and then discover QRP aint't gonna do much for them, unless they use digital modes or CW. Then they find out that an add-on 100 W amplifier.....A REAL good one with filters, is going to cost almost $1,000.00USD.When my SDR 1000 dies, I will fork out the $1500.00 for a Flex SDR 3000, if they're still available.Fred

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